1. Technical Field
The present invention relates an apparatus for manufacturing molten irons that prevent fine iron ore from adhering to itself within a cyclone in the fluidized-bed reactor in a smelting reduction process using fine ore.
2. Background Art
The iron and steel industry is a core industry that supplies the basic materials needed in construction and in the manufacture of automobiles, ships, home appliances, and many of the other products we use. It is also an industry with one of the longest histories that has progressed together with humanity. In an iron foundry, which plays a pivotal roll in the iron and steel industry, after molten iron, which is pig iron in a molten state, is produced by using iron ore and coal as raw materials, steel is produced from the molten iron and then supplied to customers.
At present, approximately 60% of the world's iron production is realized by using the blast furnace process developed from the 14th century. In the blast furnace process, cokes produced by using bituminous coal and iron ore that have undergone a sintering process are charged into a blast furnace, and hot gas is supplied to the blast furnace to reduce the iron ore to iron, to thereby manufacture molten iron.
The blast furnace process for manufacturing molten iron requires materials that have the rigidity beyond a certain level and that can secure breathability in a blast furnace. Therefore, the carbon materials used for fuel and plasticizes lean against the coke, which produces specific fuel coke. Sintered ores, which passed a serial process, are mainly used as iron sources.
Accordingly, in the modern blast furnace method, it is necessary to include raw material pre-processing equipment such as coke manufacturing equipment and sintering equipment to process iron ore, and not only is it necessary to obtain accessory equipment in addition to the blast furnace, but equipment to prevent and minimize the generation of pollution in the accessory equipments are needed. The amount of investment, therefore, is considerable and ultimately increasing manufacturing costs.
In order to solve these problems of the blast furnace method, much research is being conducted into a smelting reduction process for manufacturing molten irons in many countries by directly using raw coal as a fuel and a reducing agent, and also directly using fine iron ore that makes up 80% or more of output ore in the world as an iron source.
Two steps of a reducing method including preliminary reduction and final reduction of ore are generally used in the smelting reduction process. The conventional smelting reduction apparatus consist of a fluidized-bed reduction reactor that forms a bubble fluidized-bed and a melter-gasifier connected the bubble fluidized-bed that forms a coal packed-bed. The fine iron ore at room temperature and additives are charged in to the melter-gasifier and are pre-reduced.
Since hot reducing gas is supplied to the fluidized-bed reduction reactor from the melter-gasifier, the fine iron ore in a room temperature and additives contact the hot reducing gas, and then their temperatures are raised. Simultaneously, fine iron ore at room temperature and additives are reduced with at a ratio of equal to or more than 90% and is plasticized with a ratio equal to or more than 30% and then charged into the melter-gasifier.
Meanwhile, a plurality of cyclones collect ore in the fluidized-bed reduction reactor as fine iron ore particles, drop them by gravity, and recirculate it the fluidized-bed.
A high density flow of the fine iron ore is formed in the cyclone. At this time, operating temperature of the fluidized-bed reduction is equal to or more than 700 degrees, and fine iron ore continuously contacts the reducing gas. In this condition, adhesiveness of the surface of fine iron ore, that is, a state of physical adhesion between fine iron ore particles, becomes high.
Therefore, fine iron ore particles are adhered to each other in the cyclone and such adhesion is promoted more and more since the cyclone is continuously vibrated by the reducing gas flow in operation of the fluidized-bed reduction reactor.
If a size of the fine iron ore particles become equal to or more than a predetermined size, the cyclone is blocked with the adhesive materials, and thereby the flow of fine iron ore is interrupted. As described above, if the flow is interrupted in the cyclone, a large loss of fine iron ore occurs, since the fine iron ore cannot be recovered
Moreover, since considerable working hours are necessary to remove the adhesive materials formed in the cyclone, the blockage phenomenon of the cyclone due to the adhesive materials largely reduces an operating ratio of the fluidized-bed reduction reactor.
In order to solve the above problems, the present invention is contrived to provide an apparatus for manufacturing molten iron that prevent agglomeration of fine iron ore particles in a cyclone from forming during fluidizing a fine iron ore reduction process.